The present invention relates to a device for generating electric power in a wellbore formed in an earth formation, the wellbore being provided with a conduit for passage of a stream of hydrocarbon fluid produced from the earth formation.
Downhole electric power generating devices for electronic data communication or for signal transmission, have been applied in the form of downhole turbines drive by the stream of hydrocarbon fluid. However such devices have certain drawbacks and are prone to failure.
It is an object of the invention to provide an improved device for generating electric power in a wellbore formed in an earth formation.
In accordance with the invention there is provided a device for generating electric power in a wellbore formed in an earth formation, the wellbore being provided with a conduit for passage of a stream of hydrocarbon fluid produced from the earth formation, the power generator comprising a mandrel adapted to be incorporated in the conduit, the mandrel being provided with a side pocket arranged to receive a thermoelectric power generator having a first wall in thermal contact with the stream of hydrocarbon fluid and a second wall in thermal contact with the earth formation surrounding the wellbore.
The stream of hydrocarbon fluid is significantly hotter than the earth formation surrounding the wellbore, so that a temperature difference is created between the two junctions of the thermocouple which thereby generates an electric current. The current can be used to charge a rechargeable downhole battery.